"Human vision has a pretty limited response speed, so it seems pretty unlikely that PWM at a reasonable speed (hundreds of hertz to tens of kilohertz) can be directly perceived."
I make power drivers. I have this ultra-tiny one, with output scope captures. It produces ~825kHz PWM output, single-digit mV and mA ripple, 94+% efficiency depending on input voltage (output is input minus 0.2V)
I can induce sacchades in my eyes at will and at high speeds. Couple that with waving my hand in front of my face as I do that, and add in human vision persistence, and I can get artifacting that reveals flicker even at that high of a rate of PWM. Only direct battery power fails to induce that artifacting effect in my vision when I do that combination of movement.
I make power drivers. I have this ultra-tiny one, with output scope captures. It produces ~825kHz PWM output, single-digit mV and mA ripple, 94+% efficiency depending on input voltage (output is input minus 0.2V)
I can induce sacchades in my eyes at will and at high speeds. Couple that with waving my hand in front of my face as I do that, and add in human vision persistence, and I can get artifacting that reveals flicker even at that high of a rate of PWM. Only direct battery power fails to induce that artifacting effect in my vision when I do that combination of movement.